Which day trip from Lucern?

I am trying to plan a lake/mountain day trip from Luzern for our family trip in June. Children 18,20, I wonder if anyone has a preference of Pilates, Rigi or Titlis? With our Swiss pass it seems Rigi is totally free which is desirable, but wanted others opinion. We will just have left Berner Oberland before Luzern and will go on to Zurich after Luzern. Other fun/ adventurous suggestions appreciated in place of mountain excursion as well. Thank you!

Combining the lake and a mountain trip can easily be done if you go to Mount Rigi. You can also do a bit of hiking there. There are less hiking options for the other two mountains. Details of all these day trips can be found here, so that may help to make a choice. The children may like the open air cable car of Stanserhorn, so that's another alternative in the region.